Identifying carcinogenic activity of methylated and non-methylated polycyclic aromatic hydrocarbons (PAHs) through electronic and topological indices

Braga, Rafael Silveira; Barone, P.M.V.B.; Galvão, Douglas S.

doi:10.1590/s0103-97332000000300013

Cited by 14 publications

(3 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The fact that the specific affinity q max /K S is estimated from q max and K S might lead to the conclusion that Equation 4 should contain descriptors similar to those in Equations 2 and 3. The descriptors in Equation 3, however, differ, and the only high correlation is between RadOfGyration of Equation 3 and PHI of Equation 4. The apparent contradiction is explained by q max /K S not correlating with either q max or K S .…”

Section: Development Of Qsarsmentioning

confidence: 98%

“…The predictive value of QSARs is evident for large and diverse classes of chemicals for which experimental data are limited. In the case of PAHs, useful relationships are available for PAH toxicity [3,4] and physicochemical properties [5] but not for biodegradability. A recent attempt to construct a QSAR for the specific first‐order biotransformation rate coefficient was unsuccessful [6].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Quantitative structure‐activity relationships for kinetic parameters of polycyclic aromatic hydrocarbon biotransformation

Dimitriou-Christidis¹,

Autenrieth²,

Abraham³

2008

Enviro Toxic and Chemistry

View full text Add to dashboard Cite

Quantitative structure-activity relationships (QSARs) were developed for three Monod-type parameters--qmax, Ks, and qmax/Ks--that express the kinetics of polycyclic aromatic hydrocarbon (PAH) biotransformation by Sphingomonas paucimobilis strain EPA505. The training sets contained high-quality experimental values of the kinetic parameters for 20 unsubstituted and methylated PAHs as well as values of 41 meaningful molecular descriptors. A genetic function approximation algorithm was used to develop the QSARs. Statistical evaluation of the developed QSARs showed that the relationships are statistically significant and satisfy the assumptions of linear-regression analysis. The Organization for Economic Co-operation and Development principles for (Q)SAR validation were followed to evaluate the developed QSARs, which showed that the QSARs are valid. The QSARs contain spatial, spatial and electronic, topological, and thermodynamic molecular descriptors. Whereas spatial descriptors were essential in explaining biotransformation kinetics, electronic descriptors were not. Mechanistic interpretation of the QSARs resulted in evidence that is consistent with the hypothesis of membrane transport as being the rate-limiting process in PAH biotransformation by strain EPA505. The present study demonstrates the value of QSAR not only as a predictive tool but also as a framework for understanding the mechanisms governing biodegradation at the molecular level.

show abstract

Section: Development Of Qsarsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Quantitative structure‐activity relationships for kinetic parameters of polycyclic aromatic hydrocarbon biotransformation

Dimitriou-Christidis¹,

Autenrieth²,

Abraham³

2008

Enviro Toxic and Chemistry

View full text Add to dashboard Cite

show abstract

“…An HMO based local density of states (LDOS) analysis over K, L and bay regions (10) could provide, however, a pattern that could be correlated with carcinogenic power for methylated PAH molecules but could not give correlations with carcinogenicity of non-methylated PAH. An alternative similar simpler methodology did not give better dependence on carcinogenicity of methylated and non-methylated PAHs (11). These results show disagreement in case of highly carcinogenic 7,12-dimethylbenz[a]anthracene (DMBA), 7-MBA, 12-MBA and also moderately carcinogenic 6-MBA.…”

Section: Introductionmentioning

confidence: 96%

QSAR FOR CARCINOGENICITY IN METHYL BENZ[a]ANTHRACENES AND BENZ[c]ACRIDINES USING π-ELECTRONIC DATA IN A SELF-CONSISTENT FIELD MO THEORY

Dhar¹

2006

Polycyclic Aromatic Compounds

View full text Add to dashboard Cite

Quantitative structure-activity relationships were obtained for series of methyl benz [a]anthracene and benz [c]acridine molecules. Regression analysis was done on π-electronic indices associated with specified molecular regions of importance named "bay" (Q AB ),"K" (Q K ), "L"(QL), N-heteroatomic position (QN) and superdelocalizability index (SK associated with K-region) of these molecules to correlate with reported experimental carcinogenicity indices. The electronic indices calculated earlier for methyl benz[c]acridines by a self-consistent field molecular orbital theory named 'two-parameter omega-technique' are reported from unpublished data. 'Two-parameter omega -technique' used successfully for methyl derivatives earlier, was modified to incorporate the N-heteroatom present in benzacridines. Reported log (carcinogenicity indices) for a series of 14 methylbenz[a]anthracenes are found to be positively correlated with Q AB having correlation coefficient (R = 0.65) which is increased to 0.82 by combining this correlation equation with that depending on QL which is negatively correlated (R = 0.7) with reported log (carcinogenicity indices). Highly significant positive correlations of QN (R = 0.92), Q AB (R = 0.85) and SK (R = 0.90) and negative correlations of QL (R = 0.94) for a , Keya Dhar and Keya Roy is the one and the same person. 385 386 K. Dhar series of 9 methyl benz[c]acridines with reported cancer indices are obtained. Combining the negative correlation equation dependent on QL with the best positive correlation equation involving QN cannot improve the correlation coefficient, but still gives the best value of (R = 0.94) for methylbenz[c]acridines. The carcinogenicities of a series of methyl derivatives of benz[a]anthracene and benz [c]acridines are discussed in terms of the relationships with frontier electron density and superdelocalizability of specific regions of molecular periphery of these molecules. π-Electron density obtained by combination of electron-density of a low reactive L-region with a highly reactive region like bay-region, K-region or nitrogen-atom position of molecular periphery is found to be the best indicator of carcinogenicity in a series of methyl benz [a]anthracenes and benz [c]acridines.

show abstract

A DFT‐Based Investigation of Hydrogen Abstraction Reactions from Methylated Polycyclic Aromatic Hydrocarbons

2008

View full text Add to dashboard Cite

The growth of polycyclic aromatic hydrocarbons (PAHs) is in many areas of combustion and pyrolysis of hydrocarbons an inconvenient side effect that warrants an extensive investigation of the underlying reaction mechanism, which is known to be a cascade of radical reactions. Herein, the focus lies on one of the key reaction classes within the coke formation process: hydrogen abstraction reactions induced by a methyl radical from methylated benzenoid species. It has been shown previously that hydrogen abstractions determine the global PAH formation rate. In particular, the influence of the polyaromatic environment on the thermodynamic and kinetic properties is the subject of a thorough exploration. Reaction enthalpies at 298 K, reaction barriers at 0 K, rate constants, and kinetic parameters (within the temperature interval 700-1100 K) are calculated by using B3LYP/6-31+G(d,p) geometries and BMK/6-311+G(3df,2p) single-point energies. This level of theory has been validated with available experimental data for the abstraction at toluene. The enhanced stability of the product benzylic radicals and its influence on the reaction enthalpies is highlighted. Corrections for tunneling effects and hindered (or free) rotations of the methyl group are taken into account. The largest spreading in thermochemical and kinetic data is observed in the series of linear acenes, and a normal reactivity-enthalpy relationship is obtained. The abstraction of a methyl hydrogen atom at one of the center rings of large methylated acenes is largely preferred. Geometrical and electronic aspects lie at the basis of this striking feature. Comparison with hydrogen abstractions leading to arylic radicals is also made.

show abstract

Identifying carcinogenic activity of methylated and non-methylated polycyclic aromatic hydrocarbons (PAHs) through electronic and topological indices

Cited by 14 publications

References 15 publications

Quantitative structure‐activity relationships for kinetic parameters of polycyclic aromatic hydrocarbon biotransformation

Quantitative structure‐activity relationships for kinetic parameters of polycyclic aromatic hydrocarbon biotransformation

QSAR FOR CARCINOGENICITY IN METHYL BENZ[a]ANTHRACENES AND BENZ[c]ACRIDINES USING π-ELECTRONIC DATA IN A SELF-CONSISTENT FIELD MO THEORY

A DFT‐Based Investigation of Hydrogen Abstraction Reactions from Methylated Polycyclic Aromatic Hydrocarbons

Contact Info

Product

Resources

About